Fluid pressure braking system



Aug. 15, 1933. w A, BRECHT FLUID PRESSURE BRAKING SYSTEM Filed March 7, 1931 vYA.

INVENTOR Mif/b/V/fffz ATTORNEY U35 scope of the application of which will be inillustrated ball-check valve 84 and the pipe 85.

Patented Yug. 15, 1933 i i UNITED STATES PATENT OFFICE `FLUID PRESSURE BRAKING `SYSTEM i Winston A. Brecht, Pittsburgh, Pa., assigner to Westinghouse Electric & Manufacturing Com` `pany a Corporation of Pennsylvania Applieaiion March 7, 1931. serial No. 520,830

` 6 Claims. (Cl. 303-22) This invention relates generally to braking cylinder adapted for use in a fluid-pressure braksystems andparticularly to fluid-pressure braking SySteIiL ing systems for motor vehicles, i Referring now to the drawing, 10 designates The object oi the invention, "generally stated, a brake cylinder of any suitable design adapted is the provision ofabraking system that shall for use in duid-pressure braking Systems. AS ,5 be simple and `eiiicient"` in operation and readily Shown in Fig. 4, e DiStOIl 11 iS mounted in the 60 and economically manufactured and` installed. brake Cylinder 10 eflddSDOSed OI ODeIeOIl by A more specific object of the invention is to Ineens 0f any Suitable fluid, Sileh eS Oil, Silbprovide for` subjecting the fluid, provided in a iected to a pressure. Any well-known type of `braking system for transmitting a braking effort, brake rigging may be employed for connecting D to `a pressure proportional to the load carried the piston llitO the brekeShOe 15. 65 by the vehicl.` i f In the structureillustrated, the brake rigging A further object of the invention is to utilize comprises a Geil Spring 12 and e Spring-biased the movements of the body 'ci a vehicle relative Cap 13 meunted in the Cylinder 10 and a brake to the truck frame caused by the vehicle movrod 14, Which has One end Connected t0 the ,ing over irregularities in the road for delivering brake shoe 15 and the other end seated in a a fluid into a braking system and subjecting said recess formedin the cap 13. iluid to the weight of `the vehicle for transmit- As Willbe observed in Fig. 11, a triple valve ting a braking effort proportional to the load 21, 0f any eOIlVelltiOIlai type, iS lliiliZed OI C011* carried by 'the vehicle,` trolling the movementsofthe iiuid in the brak- `Another object of the invention is to utilize ing system. The triplevalve 21 may be actuated the medium, .interposed between the body of. a to its on position invarious ways. The means vehicle and the fluid of the braking system, ,for shown for actuating the valve 2l comprises a subjectingsaid fluid to a pressure proportional" piston 22- mounted in the cylinder 23 and dis- 25 to the weight carried bythe vehicle and for supposed to be subjected to a pressure which moves i i porting resiliently the body `of the vehicle. it against a coil spring 17 which biases the triple 80 Other objects of `the invention will, in part, valve to its offi position. As illustrated a footbe obvious and, in part, appear hereinafter. Y pump 24,'connected tothe cylinder 23 at a point This invention, accordingly,` is disclosed in the by means ofthe control pipe 27, is provided `embodiment thereof shown in the accompanyior supplying a fluid under pressure to the cylining drawing and comprises the features of conder 23. The plunger of the foot-pump 24 is struction, the combination of elements and the biased upwardly Vby means of the illustrated arrangement of parts which` will be exemplified spring. The control pipe 27 is also connected inthe construction hereinafter set forth and the to the uid reservoir 48 through means of the dicated in the claims. For the purpose of keeping the control pipe 27,

For affller understanding `of the objects of the Cylinder 23` end Jile feet-Dump 24 fully the invention, reference shouldn@ had to the harsed Wlth a fluid, e hand-Operated temp 26 following detailed description, taken in connec-,V 1S connecied to the end 0f the Contiolpme 27- 40 tion with the accompanying drawing, inwhich-f BY Operatmg, the hanq'pump 26 fluid 1S .drawn 5 y l from the fluid reservoir 48 through the pipe 85, Figure 1` is a view, 1n sideelevation, of a tm b u hl k l 84 d. t th t 1 fluid-pressurebraking system, forv one truck of pas. e a Tc ec Va ve an m o e 'con ro a vehicle embod in the fe ture f pipe 27'. As is apparent, the hand-pump 26 need t, ,y g a s o my in", be operatedonly to take care of any diminution Ven-10n' Q of the control luidresulting from leakage, and 1 Fig. 2 1s a view, in vertical section, of a conthe like. l *i 00 miner, CODStlilctd in. .acordan Wthfmy in' fAs a Vmeansifor subjecting the uid provided $23511; .gstesrrllbiftlig pfvldke'd mi@ in -a braking system for transmitting a braking le a Ta mg e effort to a pressure proportional to the load 50 fflfO ihpleslsli'lllen proportional i0 the load Cacarried by the vehicle, a container 29, shown in 105 'Ile `Y e Ve 1C e; i Fig.` 2, is provided. The container comprises Fig. 3`iSef View, iIlVeliiieel Section, 0f a triple two relatively movable telescopic cylinders 30 va/edadapted fo clcntrollintg the operations of, and 32 which are mounted between the body a u1 -pressure ra ing sys em,and, and the truck of a vehicle. The head 31 of `5;; Fig. 4 isla view,in vertical section, of a brake `cylinder 30 is adapted to be mounted on thello K brake cylinder.

truck of the vehicle (not shown). Attached to the cylinder head 33 of cylinder 32 is a body plate 34 which may be connected to the body of the vehicle by means of stud bolts 35.

The container 29 is lled with oil and compressed air. The compressed air is utilized for subjecting the oil to a pressure proportional to the load carried by the vehicle and for supporting resiliently the body carried by the truck of the vehicle. The compressed air, in the container 29, is trapped between the cylinder head 33 and the oil which is alwaysmaintained above the open end of the cylinder 32.

In order to supply compressed air to the container 29, a pipe nipple 60 which may be connected to any suitable source of compressed air, a ball check valve 58 and a duct 57, are provided. When a source of compressed air is connected to the pipe nipple 60, air flows past the ball check valve 58 to the air duct 57 and thence, through the oil, to the upper part of the container 29.

As will be readily understood, it is only necessary to have the container 29 sealed to hold oil subjected to a pressure, since the oil level is always maintained above the open end of the cylinder 32. As a means for sealing the container 29 for oil subjected to a pressure, piston rings 36, of any suitable type, are utilized. The

L rings 36 are disposed intermediate the cylinders 36 and 32 in spaced grooves 37 of the cylinder 32. A washer 38, made of any suitable material, such as leather, isutilized as an additional ineens for sealing the container 29.

`metal annulus 39 is so beveled that the oil in Since dirt and other foreign substances are apt to enter the space between the two relatively movable cylinders and 32, a shield41 is provided.

It will be observed that, upon each application of the brakes, the amount of oil contained in the container 29 will be' diminished and, therefore, pumping means must be provided for replenishing the oil as it is forced into the As shown in Fig. 2, the pumping means comprises a cylinder 43 attached to the cylinder head 31 and disposed to receive a piston 44 having rings 45. The piston 44 is attached to the cylinder head 33 by means of a piston rod 46 which is screwed into the cylinder head 33. Y

It will be noted that any relative movements of the body with respect to the truck of the vehicle will cause the piston 44 and the cylinder 43 `to produce a pumping action. In communication with the cylinder 43 is a duct 47 which has -`a ball-check valve 52 mounted therein. The exit end 81 of the duct 47 is connected directly to a iiuid reservoir 48 by a pipe 49. The

ball-check valve 52 permits the free flow ofthe oil from the fluidreservoir 48 to the duct 47 but prevents the flow in the opposite direction. Also the duct 47 is connected to the container 29 through a ball-check valve 53 which permits the free flow of the oil from the duct 47 to the container 29 but prevents the ow in the opposite direction.

In order to prevent the pump from continuously delivering oil into the container 29, a bypass duct 54 is provided. The upper end of the by-pass duct 54 is in communication with the upper end of cylinder 43 and the lower end 82 is connected to the fluid reservoir 48 by a pipe 55.

In explaining the operation of the container 29, let it be assumed that the container 29 is charged with a fluid and compressed air, the level of the fluid being such that the lower end of the piston 44 is below the point where the by-pass duct 54 is in communication with the cylinder 43. Hence, as the body of the vehicle moves up-and-down relatively to the truck frame, the piston 44 reciprocates below the point where the by-pass duct 54 is in communication with the cylinder 43. On an upward movement of the piston 44, oil is drawn from the fluid reservoir 48 through the pipe 49, past the ballcheck valve 52, and through the duct 47 into the cylinder 43. On the downward movement of the piston 44, the ball-check valve 52 prevents the return of the fluid to the fluid reservoir 48, and thus the fluid is forced into the container 29 past the ball-check valve 53. Continued operations of the foregoing reciprocating movement of the piston 44 gradually forces an additional supply of fluid into the container 29, and thus causes the piston 44 to rise, until its reciprocating movements are above the point where the by-pass duct 54 is in communication with the cylinder 43. So long as the reciprocating movements of the piston 44 are above the point .where the by-pass duct 54 is in communication with the cylinder 43, no additional fluid is delivered to the container 29. On an upward movement of the piston 44, as previously explained, uid is drawn from the fluid reservoir 48 through the pipe 49, past the ball check valve 52, and the duct 47 into the cylinder 43, but on the downward movement of the piston the oil .is forced back into the fluid reservoir 48 through. the by-pass duct 54 and the pipe 55. Therefore, by means of the by-pass duct 54, the action of the cylinder 43 and the piston 44 is suchk that the uid in the container 29 is maintained at a predetermined level, so that a suflicient quantity of fluid is always in readiness for making a series of brake applications.

Suppose, for example, that, after several brake applications are made, the fluid in the container 29 diminishes to a point where the piston 44 again reciprocates below the point where the by-pass duct 54 is in communication with the cylinder 43. Under this supposition, the action of the cylinder 43 and the piston 44 again forces oil past the ball check valve 53 into the container 29. This action continues until-a sufiicient quantity of oil is forced into the container 29 to raise the piston 44 above the point where the by-pass duct 54 is in communication with the cylinder 43.

As shown in Fig. 1, the triple valve 21 is connected to the outlet 56 of the container 29 by a pipe 66; to the brake cylinder 10 by a pipe 64, and to the fluid reservoir 48 by a pipe 65 that is connected to the pipe which leads to the fiuid reservoir 48.

In explaining the operation of the triple valve 21, in combination with the container 29, let it be assumed that the container 29 is charged with a uid and compressed air, that the'spring 17 is biasing thetriple valve 21 to its "off position, and that thewcylinder 23, the control pipe 27 and the foot-pump 24 are fully charged with a fluid. When the triple valve 21 is in the off position, the brake cylinder 10 is in communication with the fluid reservoir 48, so that the lluidin the brake cylinder 10, under the biasing force of the spring 12, is forced through the pipe 64, the triple valve 21the pipe 65, andthe to its on position. When the triple valve 21 is actuated to its on position,` communication between the brake cylinder l0 and the fluid reservoir 48 is interrupted, but communication is established between the container 29 and the brake cylinder 10. Therefore, fluid under pressure flows from the container 29 through the outlet 56, the pipe 66, the tripleV valve 21, and the pipe 64 to the brake cylinder 10. Since the brake cylinder is directly connected to the container 29, a braking action is effected that is proportional to the load` carried by the Vehicle. The brakes may be released by the operator removing his foot from the plunger of the footpump 24, thus allowing the spring 17 to again bias the triple valve 21 to its off position, whereupon communication between the brake cylinder 10 and the container 29 is blanked and communication between the brake cylinder 10 and the fluid reservoir 48 is re-established- Therefore, it willbe seen that I havediscloserl a device for subjecting the iluid provided in a braking system, for transmitting a braking force, to a pressure proportional to the load carried by the vehicle.

I would state, in conclusion, that, while the illustrated example constitutes a practicalembodiment of my invention, I do not limit myself strictly to the exact details herein illustrated, since modifications of theV same can be considerably varied without departing from the spirit of the invention as definedV in the appended claims.

I claim as myinvention: i

l. A fluid braking system for vehicles, including means forr controlling the movements of a fluid provided in a braking system, in combination with a load-carrying `container connected to the braking system for subjecting saidiluid to a pressure, and means disposed for operation by the movements of the vehicles for maintaining a predetermined amount of said fluid in said container. i

2. A fluid braking system for vehicles, including means for controlling the movements of a fluid provided in a braking system, in combination with a load-carrying container connected to the braking system for subjecting said fluid to a pressure,v and means provided within said container and disposed for operation by the movements of the Vehicle for maintaining a predetermined amount of said fluid in said vcontainer.

3. A fluid braking system for vehicles, including means `for controlling the movements of a substantially non-compressible fluid provided in a braking system, in combination with a loadcarrying means that is connected to the braking system and adapted to entrap a compressible medium for subjecting said substantially noncompressible fluid to a pressure, and means for maintaining apredetermined amount of said substantially non-compressible fluid in said loadcarrying means. f

4. A fluid braking system for vehicles, including means for controlling the movements of a substantially non-compressible fluid provided in a braking system, in combination with a load-V carryingmeans that is connected to the braking system and adaptedrto entrap a compressible medium for subjecting said substantially nonccmpressible fluid to a pressure, and means disposed for operation by the movements of the vehicle for maintaining a predetermined amount of said substantially non-compressible fluid in said load-carrying means.

5. A fluid braking system` for vehicles including means for controlling the movements of a substantially non-compressible fluid provided in the braking system, in combination with a loadcarrying container comprising two relatively movable telescopic cylinders connected to the braking system and adapted to entrap a compressible medium, a fluid pump mounted within the container and actuated by the relative move,- ments of the telescopic cylinders, means associated with the pump `for maintaining the noncompressible fluid at a predetermined level within the container, and means whereby a compressible medium may be introduced into the container above the level of the non-compressible fluid.

6. A load-carrying device comprising, in combination, two relatively movable elements forming a fluid container, adapted to entrap a compressible medium, a reservoir for containing a `supply of substantially non-compressible fluid,

means interconnecting the fluid container and the reservoir, means actuated by the relative movements of the said elements for maintaining the non-compressible fluid at a predetermined level within the container, and means whereby a compressible mediumvmay be introduced into the fluid.

WINSTON A. BRECHT.

container above the level of the non-compressible 

